Determining the Magnetic Field in the Atmosphere of a Solar Active Region Observed by the CLASP2.1 Sounding Rocket Experiment

Abstract

We determine magnetic fields from the photosphere to the upper chromosphere combining data from the Hinode satellite and the CLASP2.1 sounding rocket experiment. CLASP2.1 provided polarization profiles of the Mg~{|sc ii} $h$ and $k$ lines, as well as of the Mn~{|sc i} lines around 2800~{|AA}, across various magnetic structures in an active region, containing a plage, a pore, and the edges of a sunspot penumbra. By applying the Weak-Field Approximation (WFA) to the circular polarization profiles of these spectral lines, we obtain a longitudinal magnetic field map at three different heights in the chromosphere (lower, middle, and upper). This is complemented by data from Hinode (photospheric magnetic field), IRIS, and SDO (high-spatial-resolution observations of the chromosphere and corona). We quantify the height expansion of the plage magnetic fields and find that the magnetic fields expand significantly in the middle chromosphere, shaping the moss observed above in the transition region and corona. We identified an area with polarity reversal at the upper chromosphere around the edge of the pore, suggesting the presence of a magnetic discontinuity in the upper chromosphere. Transient and recurrent jet-like events are observed in this region, likely driven by magnetic reconnection. Around the penumbral edge, we find large-scale magnetic fields corresponding to the superpenumbral fibrils seen in the upper chromosphere. In the superpenumbral fibrils, we find Zeeman-induced linear polarization signals, suggesting the presence of a significantly inclined magnetic field, as strong as 1000~G in the upper chromosphere.

22 pages, 11 figures. Accepted for publication in The Astrophysical Journal

References in corpus (17)

• The Solar Optical Telescope for the Hinode Mission: An Overview
• Magnetic Diagnostics of the Solar Chromosphere with the Mg II h-k Lines
• Mapping Solar Magnetic Fields from the Photosphere to the Base of the Corona
• The magnetic sensitivity of the Mg ii k line to the joint action of Hanle, Zeeman and magneto-optical effects
• The magnetic sensitivity of the resonance and subordinate lines of Mg II in the solar chromosphere
• TIC: A Stokes inversion code for scattering polarization with partial frequency redistribution and arbitrary magnetic fields
• Upper Chromospheric Magnetic Field of a Sunspot Penumbra: Observations of Fine Structure
• Transverse motions in sunspot super-penumbral fibrils
• Tomography of a solar plage with the Tenerife Inversion Code
• New light on an old problem of the cores of solar resonance lines
• Chromospheric magnetic field: A comparison of He I 10830 A observations with nonlinear force-free field extrapolation
• Empirical relations between the intensities of Lyman lines of H and He${}^{+}$
• The circular polarization of the Mn I resonance lines around 280 nm for exploring chromospheric magnetism
• Unveiling the True Nature of Plasma Dynamics from the Reference Frame of a Super-penumbral Fibril
• Effects of spectral resolution on simple magnetic field diagnostics of the Mg II h & k lines
• Evidence for the Operation of the Hanle and Magneto-Optical Effects in the Scattering Polarization Signals Observed by CLASP2 Across the Mg II h and k Lines
• Exploring magnetic field properties at the boundary of solar pores: A comparative study based on SDO-HMI observations